1. Technical Field
The present disclosure relates to a method for operating a hydrogen generator, a hydrogen generator, and a fuel cell system.
2. Description of the Related Art
A hydrogen-containing gas, which serves as a fuel for a fuel cell system, is normally produced by, for example, reforming a source gas such as a hydrocarbon fuel with a reformer. The source gas may contain a sulfur compound used as an odorant or derived from the raw material. Since the sulfur compound may poison a reforming catalyst included in the reformer, the sulfur compound contained in the source gas needs to be removed before the source gas is fed to the reformer.
A known example of a desulfurizer that removes the sulfur compound is a hydrodesulfurizer. In a hydrodesulfurizer, desulfurization is performed by reacting the sulfur compound with hydrogen in the presence of a suitable catalyst to produce hydrogen sulfide and causing the hydrogen sulfide to be adsorbed to a catalyst. Since the hydrodesulfurization requires hydrogen, part of the hydrogen-containing gas produced by the reformer is commonly fed to the hydrodesulfurizer as a recycle gas (e.g., see Japanese Unexamined Patent Application Publication 2002-356308, which is referred to as “PTL 1” hereinafter).
However, it cannot be said that the risk of the reformer being degraded due to shortage of water vapor available in the reformer which may occur in the case where the recycle gas is fed to the hydrodesulfurizer has been studied in PTL 1 to a sufficient degree.